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Elena-2011 [213]
2 years ago
10

The percentage of radioactive atoms that decay during one (1) half-life ____________.

Physics
2 answers:
Rina8888 [55]2 years ago
4 0

Answer:

is the same

Explanation:

Half life is define as the time it take for fifty percentage of a radioactive material to disintegrate. After the first half-life passes, half (fifty percentage) of the remaining radioactive material will disintegrate in the next half-life. Then, half of that amount in turn disintegrate in the following half-life and the halving continues.

laiz [17]2 years ago
3 0

Answer:50% of its starting atomic mass

Explanation:

The radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation. The half life is the time taken for the activity of a given amount of a radioactive substance to decay to half of its starting mass.

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Some plants disperse their seeds when the fruit splits and contracts, propelling the seeds through the air. The trajectory of th
Anton [14]

Answer:

Option B, 93 cm

Explanation:

An diagram of the seed's motion is attached to this solution.

This is very close to a projectile motion question. And the quantity to be calculated, how far along the grant a seed released would travel is called the Range.

And this would be obtained from the equations of motion,

First of, the height of the plant is related to some quantities of the motion with this relation.

H = u(y) t + 0.5g(t^2)

U(y) = initial vertical component of velocity = 0 m/s, H = height at which motion began, = 20cm = 0.2 m

That means t = √(2H/g)

The horizontal distance covered, R,

R = u(x) t + 0.5g(t^2) = u(x) t (the second part of the equation goes to zero as the vertical component of the acceleration of this motion is 0)

(substituting the t = √(2H/g) derived from above

R = u(x) √(2H/g)

Where u(x) = the initial horizontal component of the bomb's velocity = maximum initial speed, that is, 4.6 m/s, H = vertical height at which the seed was released = 20 cm = 0.2 m, g = acceleration due to gravity = 9.8 m/s2

R = 4.6 √(2×0.2/9.8) = 0.929 m = 0.93 m = 93 cm. Option B.

QED!

6 0
2 years ago
Read 2 more answers
A cargo elevator on Earth (where g = 10 m/s2) lifts 3000 kg upwards by 20 m. 720 kJ of electrical energy is used up in the proce
MakcuM [25]

Answer: 83%

Explanation:

Efficiency of the process = work output/work input × 100%

Work input is the energy used up in the process = 720,000Joules

Work output = Force × distance

= (3000×10)× 20

= 600000 Joules

Efficiency= 600000/720000 × 100

= 0.83×100

= 83%

8 0
3 years ago
A stone was projected at an angle of 40o and initial velocity of 20m/s. (a.)Determine the time of flight  (b)Maximum height.
makkiz [27]

Answer:

A.) 1.3 seconds

B.) 0.42 m

Explanation:

A.) You are given the angle of projection to be 40 degrees and initial velocity of 20m/s. 

At vertical component

U = Usin 40 that is,

U = 20sin40

Using the first equation of motion under gravity

V = U - gt

Let V = 0

0 = UsinØ - gt

gt = UsinØ

t = UsinØ/g

Where U = 20 m/s

Ø = 40 degree

g = 9.8 m/s^2

Substitutes all the parameters into the formula

t = 20sin40/9.8

t = 1.3 seconds

Total time of flight T = 2t

T = 2 × 1.3 = 2.6 s

B.) To calculate the maximum height,

You will use the formula

V^2 = U^2 - 2gH

At maximum height, V = 0

2gH = Usin^2Ø

H = Usin^2Ø/ 2g

Substitutes all the parameters into the formula

H = 20 sin^2(40) ÷ 2(9.8)

H = 8.2635/19.6

H = 0.42 m

6 0
2 years ago
A box rests on top of a flat bed truck. the box has a mass of m = 18 kg. the coefficient of static friction between the box and
konstantin123 [22]
For this case, the first thing you should do is write the kinematic motion equation of the block.
 We have then:
 vf = vo + a * t
 Where,
 vf: Final speed.
 vo: Initial speed.
 a: acceleration.
 t: time.
 Substituting the values:
 (16) = (0) + a * (16)
 Clearing the acceleration:
 a = 16/16 = 1m / s ^ 2
 Note: the other data for this case are not used in this problem.
 answer:
 The acceleration of the box is 1m / s ^ 2
5 0
2 years ago
It has been argued that power plants should make use of off-peak hours to generate mechanical energy and store it until it is ne
sdas [7]

Answer:

Explanation:

90 rpm = 90 / 60 rps

= 1.5 rps

= 1.5 x 2π rad /s

angular velocity of flywheel

ω = 3π rad /s

Let I be the moment of inertia of flywheel

kinetic energy = (1/2) I ω²

(1/2) I ω² = 10⁷ J

I = 2 x  10⁷ / ω²

=2 x  10⁷ / (3π)²

= 2.2538 x 10⁵ kg m²

Let radius of wheel be R

I = 1/2 M R² , M is mass of flywheel

= 1/2 πR² x t x d x R² , t is thickness , d is density of wheel .

1/2 πR⁴ x t x d = 2.2538 x 10⁵

R⁴ = 2 x 2.2538 x 10⁵ / πt d

= 4.5076 x 10⁵ / 3.14 x .1 x 7800

= 184

R= 3.683 m .

diameter = 7.366 m .

b ) centripetal accn required

= ω² R

= 9π² x 3.683

= 326.816 m /s²

3 0
2 years ago
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